Flow cytometers are valuable tools for the rapid analysis of cells and macromolecules for both research and diagnostic purposes. Ideally, flow cytometry based analysis could benefit more researchers and clinicians if the units were more affordable, smaller, and even portable. New fabrication techniques and design approaches developed in the microfluidics and lab-on-a-chip communities have great potential to impact the flow cytometry field. We have developed a dielectrophoresis (DEP)-based particle focusing channel that eliminates the need for the sheath flow used in conventional flow cytometers. This device utilizes annular electrodes that generate a negative dielectric force to focus particles in the center of the channel flow stream. The only fluid entering the flow cell is the analyte suspension. By eliminating hydrodynamic focusing and the requirement for complex macrofluidics and large volumes of sheath buffer, smaller, less complex and more affordable cytometers are enabled. The goal of the effort described in this proposal is to modify our current proof-of-principle design to make significant advances toward an improved, commercializable flow cytometry unit. Fluid dynamics simulations will be used to refine/redesign the DEP focusing channel to optimize particle focusing and achieve higher flow rates. A more facile fabrication method will be developed to yield a potentially disposable, credit-card sized focusing cartridge based upon the improved channel design. Finally, the focusing cartridge will be integrated with a small, commercially available multi-wavelength fluorescence optics detection unit and a fluorescence excitation source to yield a working prototype DEP-focused flow cytometry unit. The long-term goal of this project is to yield a small footprint, or perhaps even hand held, flow cytometer that could be commercialized as a high-performance, low-cost alternative to conventional flow cytometers.